168s and 170s can not work in multiple, the 168s had their couplers modified to work with Turbos, similarly Chiltern's 172s and the ex-Transpennie 170s. There's no fancy detection of what they're coupled to.
Sprinters and turbos have the same BSI coupler but it is wired differently through the coupler to control the hydraulic transmission, Reggie Rail had a 3 wire control (sprinter) Network South East opted for a 4 wire control (turbo) they will run together but can only run in one direction if running in the other direction the rear unit will stay in the low hydraulic drive when the lead unit goes into high hydraulic drive as it wont change up. Class 168 and 170's must be able to detect which system is in use.
The original RAIL 4 page article several years ago came from Chiltern Railways with quotes from various employees.
It also causes the buzzer to sound continuously on the sprinter of they are electrically coupled, and the Turbo won't receive buzzes from the Sprinter.
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215 has gone West for staff training for now, but several changes need to be made to the Turbos before they can work more universally in the West. The list the changes is substantial, but includes changes to ride height, fitting of saloon door controls, coupler modifications to enable electrical coupling to sprinters, modifications to electrical system to allow certain system to be powered from a remote vehicle in the event of engine failure, and several more I can't recall off the top of my head. That work is due to start in the early part of the year, although a decision is yet to be taken whether to modify the entire 165/166 fleet, or just units intended to go west. The latter will cause compatibility issues as they will no longer be compatible with their original-condition classmates.
